cyclic-gmp and Cell-Transformation--Neoplastic

Colorectal cancer (CRC) is one of the leading causes of cancer related-deaths. The risk of development of CRC is complex and multifactorial, and includes disruption of homeostasis of the intestinal epithelial layer mediated though dysregulations of tumor suppressing/promoting signaling pathways. Guanylate cyclase 2C (GUCY2C), a membrane-bound guanylate cyclase receptor, is present in the apical membranes of intestinal epithelial cells and maintains homeostasis. GUCY2C is activated upon binding of paracrine hormones (guanylin and uroguanylin) that lead to formation of cyclic GMP from GTP and activation of downstream signaling pathways that are associated with normal homeostasis. Dysregulation/suppression of the GUCY2C-mediated signaling promotes CRC tumorigenesis. High-calorie diet-induced obesity is associated with deficiency of guanylin expression and silencing of GUCY2C-signaling in colon epithelial cells, leading to tumorigenesis. Thus, GUCY2C agonists, such as linaclotide, exhibit considerable role in preventing CRC tumorigenesis. However, phosphodiesterases (PDEs) are elevated in intestinal epithelial cells during CRC tumorigenesis and block GUCY2C-mediated signaling by degrading cyclic GMP to 5`-GMP. PDE5-specific inhibitors, such as sildenafil, show considerable anti-tumorigenic potential against CRC by amplifying the GUCY2C/cGMP signaling pathway, but cannot achieve complete anti-tumorigenic effects. Hence, dual targeting the elevation of cGMP by providing paracrine hormone stimuli to GUCY2C and by inhibition of PDEs may be a better strategy for CRC prevention than alone. This review delineates the involvement of the GUCY2C/cGMP/PDEs signaling pathway in the homeostasis of intestinal epithelial cells. Further, the events are associated with dysregulation of this pathway during CRC tumorigenesis are also discussed. In addition, current updates on targeting the GUCY2C/cGMP/PDEs pathway with GUCY2C agonists and PDEs inhibitors for CRC prevention and treatment are described in detail.

Topics: Animals; Cell Transformation, Neoplastic; Chemoprevention; Colorectal Neoplasms; Cyclic GMP; Disease Susceptibility; Hemostasis; Hormones; Humans; Molecular Targeted Therapy; Paracrine Communication; Phosphoric Diester Hydrolases; Receptors, Enterotoxin; Signal Transduction

Production of cyclic guanosine monophosphate (cGMP) by guanylate cyclase is of critical importance to gastrointestinal physiology. Tight regulation of cGMP concentration is necessary for proper intestinal secretion and intestinal epithelial cell proliferative and apoptotic homeostasis. This review focuses on recent work detailing the role of a subset of transmembrane guanylate cyclases in the pathophysiology of intestinal secretory and motility disorders and intestinal epithelial cell transformation. Also considered is the potential for therapeutic manipulation of intestinal guanylate cyclase/cGMP signaling for the correction of chronic constipation and gastrointestinal cancer.. Recent work in mice and humans suggests a role for transmembrane guanylate cyclases in intestinal fluid secretion as well as hormonal enteric-renal signaling which mediates postprandial natriuresis. Transmembrane guanylate cyclases are also important in gastrointestinal transit rate and motility. Ongoing clinical trials have found that guanylate cyclase activating peptides are safe and effective in the treatment of constipation-predominant irritable bowel syndrome and chronic constipation. In addition, accumulating evidence indicates that membrane-associated guanylate cyclase receptors regulate intestinal epithelial cell homeostatic proliferation and apoptosis as well as gastrointestinal malignancy. The anticancer activity of cGMP signaling in animal studies suggests additional therapeutic applications for guanylate cyclase agonists.. Progress toward understanding gastrointestinal transmembrane guanylate cyclase/cGMP physiology has recently accelerated due to definitive in-vitro studies and work using gene-targeted animal models and has facilitated the development of safe and effective drugs designed to regulate cGMP production in the intestine. Current work should be directed toward a detailed understanding of cGMP effector pathways and the manner in which subcellular concentrations of cGMP regulate them to influence intestinal health and disease.

Topics: Animals; Apoptosis; Cell Transformation, Neoplastic; Cyclic GMP; Gastrointestinal Neoplasms; Guanylate Cyclase; Humans; Intestines; Mice; Receptors, Guanylate Cyclase-Coupled

Topics: Adaptor Proteins, Signal Transducing; Animals; beta Catenin; Calcium; Cell Cycle Proteins; Cell Differentiation; Cell Movement; Cell Polarity; Cell Transformation, Neoplastic; Cyclic GMP; Cytoskeletal Proteins; Embryo, Mammalian; Embryonic Development; Genes, Tumor Suppressor; Humans; Intercellular Signaling Peptides and Proteins; Nervous System; Phosphorylation; rac1 GTP-Binding Protein; Repressor Proteins; rhoA GTP-Binding Protein; Second Messenger Systems; Signal Transduction; Stem Cells; Trans-Activators; Transcription Factors; Transcription, Genetic; Wnt Proteins

Topics: Animals; Cell Differentiation; Cell Division; Cell Nucleus; Cell Transformation, Neoplastic; Cells, Cultured; Cyclic AMP; Cyclic GMP; Hormones; Humans; Microtubules; Protein Kinases; Subcellular Fractions

Topics: Animals; Calcium; Cell Division; Cell Transformation, Neoplastic; Cyclic AMP; Cyclic GMP; Cytotoxicity, Immunologic; Humans; Interferons; Killer Cells, Natural; Macrophages; Nucleotides, Cyclic; Phagocytosis; Receptors, Cell Surface; Viral Interference; Virus Replication

Topics: Adenosine Triphosphate; Animals; Biological Transport; Blood Cells; Cell Transformation, Neoplastic; Cyclic AMP; Cyclic GMP; Female; Guanosine Triphosphate; Humans; Kidney; Liver; Male; Neoplasms; Neoplasms, Experimental; Nucleotides, Cyclic; Rats; Receptors, Cell Surface

Topics: Adenylyl Cyclases; Animals; Bucladesine; Carcinogens; Cell Differentiation; Cell Division; Cell Transformation, Neoplastic; Cyclic AMP; Cyclic GMP; Humans; Neoplasms; Neoplasms, Experimental; Organ Specificity

Topics: Animals; Calcium; Cell Adhesion; Cell Division; Cell Movement; Cell Transformation, Neoplastic; Culture Techniques; Cyclic AMP; Cyclic GMP; Humans; Lymphocyte Activation; Lymphocytes; Microtubules; Mitogens; Mitosis; Neoplasms; Nucleotides, Cyclic

A simple model is depicted below that suggests some unifying principals in the action of cyclic nucleotides in the GO-to-G+ interconversion, differentiation, and transformation (see article). The letters with G+ subscripts (AG+ through EG+) represent cell states at different increasing levels of "determination" (see sect. vE). Cells in each of these states are continuously reproducing themselves through cell division (i.e., they are in G+). As an alternative to cell reporduction, cells at each level may move toward or enter GO, which is conceived of not only as a quiescent state but also as a state in which differentiated properties are more fully expressed. This state is designated by letters with GO subscripts (AGO through EGO). Entrance into this more expressed state will usually be reversible (nerve cells and red blood cells are two exceptions). Sometimes movement toward GO and full expression may require a number of cell divisions. Ultimately, however, there usually will be a slowing or cessation of cell division. The transformed state, according to this model, is one in which cells have lost the ability to enter the "expressed" CO state. However, they do remain differentiated in the sense that they have maintained their level of determination and can be induced to enter into the expressed state, as for example in the case of DBcAMP treatment of transformed fibroblasts. In most cases, cAMP appears to stimulate cells to proceed toward XGO (where X = A,B,C,D, or E) and toward fuller expression of their differentiated functions. It is not the sole mediator of this transition. In cell types where cAMP plays this role, transformation may arise through a defect in the ability to raise cAMP levels in response to growth-regulatory signals or in a defect in the cell's ability to respond to cAMP. In other cell types, cAMP may not be involved in the CO-to-C+ transition or may act in the opposite direction (see sect. II). It remains to be seen whether these situations are ture exceptions or whether different loci of regulation are involved. For example it is possible that in certain cases where cAMP has been shown to stimulate growth that it is stimulating growth toward a more expressed state. Other actions of cAMP relating to cell-cycle traverse have been discussed (sect. III). Investigations of the action of cGMP are still at a preliminary stage of development. There is evidence consistent with the idea that cGMP mediates conversion toward the G+ state in some

Topics: Agglutination; Animals; Cell Adhesion; Cell Differentiation; Cell Division; Cell Movement; Cell Transformation, Neoplastic; Cells, Cultured; Chick Embryo; Cyclic AMP; Cyclic GMP; DNA; Fibroblasts; HeLa Cells; Hematopoietic Stem Cells; Humans; Lectins; Liver; Liver Regeneration; Lymphocyte Activation; Mice; Mitosis; Models, Biological; Muscles; Neuroblastoma; Rats; Skin

Topics: 3',5'-Cyclic-AMP Phosphodiesterases; Adenylyl Cyclases; Carcinoma, Hepatocellular; Cell Division; Cell Membrane; Cell Transformation, Neoplastic; Cells, Cultured; Cyclic AMP; Cyclic GMP; Cytosine Nucleotides; DNA; Enzyme Activation; Enzyme Inhibitors; Fibroblasts; Growth Substances; Liver; Liver Neoplasms; Lymphocyte Activation; Lymphocytes; Melanoma; Mitogens; Neoplasms; Skin; Thymus Gland

Topics: Biological Transport; Blood; Blood Proteins; Cell Division; Cell Membrane; Cell Transformation, Neoplastic; Cells, Cultured; Contact Inhibition; Culture Media; Cyclic AMP; Cyclic GMP; Fibroblasts; Lectins; Peptide Hydrolases; Receptors, Drug

Topics: Agglutination; Alpharetrovirus; Animals; Antigens, Viral; Binding Sites; Blood; Cell Division; Cell Membrane; Cell Transformation, Neoplastic; Cells, Cultured; Culture Media; Cyclic AMP; Cyclic GMP; DNA Replication; DNA Viruses; Fibrinolysis; Glycolipids; Glycolysis; Glycoproteins; Humans; Oncogenic Viruses; RNA Viruses; Simian virus 40; Somatomedins

Topics: Adrenocorticotropic Hormone; Animals; B-Lymphocytes; Bucladesine; Cell Transformation, Neoplastic; Concanavalin A; Cyclic AMP; Cyclic GMP; Humans; Immunity; Kinetics; Lectins; Lymphocyte Activation; Lymphocytes; Models, Biological; Phagocytosis; Subcellular Fractions; T-Lymphocytes; Theophylline

Topics: Animals; Binding Sites; Cell Adhesion; Cell Division; Cell Membrane; Cell Transformation, Neoplastic; Chick Embryo; Cricetinae; Cyclic AMP; Cyclic GMP; Erythrocytes; Glycolipids; Glycoproteins; Humans; Intercellular Junctions; Kidney Tubules, Proximal; Lectins; Lipid Metabolism; Mice; Models, Biological; Neoplasm Metastasis; Neoplasms; Proteins

Topics: Animals; Cell Differentiation; Cell Division; Cell Transformation, Neoplastic; Cells, Cultured; Contact Inhibition; Cyclic AMP; Cyclic GMP; Enzyme Induction; Hormones; Microtubules; Neuroblastoma

There is growing interest in the potential use of phosphodiesterase (PDE) inhibitors for colorectal cancer (CRC) prevention and treatment. The present study has tested the idea that PDE inhibitors inhibit growth and viability of CRC cell lines by increasing cyclic guanosine monophosphate (cGMP) and activating cGMP-dependent protein kinase (PKG). Colon cancer cell lines and those with ectopic PKG2 expression were treated with membrane-permeable 8Br-cGMP or inhibitors of PDE5, PDE9, and PDE10a. Levels of cGMP capable of activating PKG were measured by immunoblotting for phosphorylation of vasodilator-stimulated phosphoprotein (VASP). The effects of treatment on CRC cell proliferation and death were measured using hemocytometry with trypan blue. Treatment with 8Br-cGMP had no effect on CRC cell proliferation or death. Endogenous PKG activity was undetectable in any of the CRC cells, but expression of ectopic PKG2 conferred modest inhibition of proliferation but did not affect cell death. Extremely high concentrations of all the PDE inhibitors reduced proliferation in CRC cell lines, but none of them increased cGMP levels, and the effect was independent of PKG expression. The inability of the PDE inhibitors to increase cGMP was due to the lack of endogenous cGMP generating machinery. In conclusion, PDE inhibitors that target cGMP only reduce CRC growth at clinically unachievable concentrations, and do so independent of cGMP signaling through PKG. SIGNIFICANCE STATEMENT: A large number of in vitro studies have reported that PDE inhibitors block growth of colon cancer cells by activating cGMP signaling, and that these drugs might be useful for cancer treatment. Our results show that these drugs do not activate cGMP signaling in colon cancer cells due to a lack of endogenous guanylyl cyclase activity, and that growth inhibition is due to toxic effects of clinically unobtainable drug concentrations.

Topics: Cell Transformation, Neoplastic; Colonic Neoplasms; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Humans; Phosphodiesterase Inhibitors; Phosphoric Diester Hydrolases; Signal Transduction

Helicobacter pylori (H. pylori) is listed as a class I carcinogen in human gastric cancer; however, the underlying mechanisms are poorly understood. In this study, we identified Protogenin (PRTG) was upregulated in both gastric cancer tissues and H. pylori-infected tissues by analyzing dysregulated genes in TCGA and GEO databases. Importantly, upregulated PRTG predicted poor prognosis of gastric cancer patients and integrative analysis revealed that PRTG served as an oncogenic protein in gastric cancer and was required for H. pylori-mediated tumorigenic activities in in vitro cellular and in vivo tumor-bearing mouse models. Mechanistically, H. pylori infection enhanced PRTG expression by promoting transcriptional factor ZEB1 stabilization and recruitment to the PRTG promoter, and which then activated the sub-following cGMP/PKG signaling pathway in bioinformatic and cellular studies. Cellular studies further confirmed that PRTG depended on activating cGMP/PKG axis to promote proliferation, metastasis, and chemoresistance of gastric cancer cells. The PKG inhibitor KT5823 played synergistic anti-tumor effects with cisplatin and paclitaxel to gastric cancer cells in in vitro cellular and in vivo tumor-bearing mouse models. Taken together, our findings suggested that H. pylori infection depends on ZEB1 to induce PRTG upregulation, and which leading to the development and progression of gastric cancer through activating cGMP/PKG signaling pathway. Blocking PRTG/cGMP/PKG axis, therefore, presents a promising novel therapeutic strategy for gastric cancer.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Transformation, Neoplastic; Cisplatin; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Databases, Genetic; Female; Gene Expression Regulation, Neoplastic; Helicobacter Infections; Helicobacter pylori; Host-Pathogen Interactions; Humans; Male; Membrane Proteins; Mice, Nude; Middle Aged; Neoplasm Invasiveness; Paclitaxel; Protein Kinase Inhibitors; Second Messenger Systems; Stomach Neoplasms; Up-Regulation; Xenograft Model Antitumor Assays; Zinc Finger E-box-Binding Homeobox 1

The cGMP signaling axis has been implicated in the suppression of intestinal cancers, but the inhibitory mechanism and the extent to which this pathway can be targeted remains poorly understood. This study has tested the effect of cGMP-elevating agents on tumorigenesis in the

Topics: Adenomatous Polyposis Coli; Animals; Apoptosis; Cell Proliferation; Cell Transformation, Neoplastic; Cyclic GMP; Female; Guanylyl Cyclase C Agonists; Intestinal Neoplasms; Male; Mice; Mice, Inbred C57BL; Peptides; Precancerous Conditions; Sildenafil Citrate

Arsenite is a well-documented human lung carcinogen but the detailed mechanisms of carcinogenesis remain unclear. In this study, human bronchial epithelial (16-HBE) cells were continuously exposed to 2.5μM arsenite for about 13 weeks to induce the phenotypes of malignant transformation. Our results showed that Nrf2 expression was gradually decreased whereas no significant change was observed on NF-κB activation with increased time of arsenite exposure. To test the roles of Nrf2-meidtaed oxidative damage in the arsenite-induced malignant transformation, we compared the levels of cGMP, PKG and oxidative damage-related indicators between arsenic-transformed cells and control cells. Our data demonstrated there were no significantly differences on the contents of cGMP, PKG, MDA and the production of ROS, but the levels of GSH and NO, the activities of SOD, tNOS and iNOS were significantly enhanced in the arsenic-transformed cells. Importantly, Nrf2 inactivation could be modulated by miR-155, and inhibition of miR-155 remarkably attenuated the malignant phenotypes and promoted apoptotic cell death in the arsenic-transformed cells. Together, our findings provide the novel mechanism that miR-155 may regulate arsenite-induced cell malignant transformation by targeting Nrf2-mediated oxidative damage, indicating that inhibition of miR-155 may be a potential strategy against lung carcinogenesis of arsenite.

Topics: Apoptosis; Arsenites; Bronchi; Carcinogens; Cell Line; Cell Transformation, Neoplastic; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Epithelial Cells; Gene Expression Regulation, Neoplastic; Humans; Lung Neoplasms; MicroRNAs; NF-E2-Related Factor 2; NF-kappa B; Nitric Oxide Synthase Type II; Oxidative Stress; Phenotype; Signal Transduction; Superoxide Dismutase; Time Factors

Protein synthesis is a tightly controlled process, and its deregulation plays an important role in tumorigenesis. Protein synthesis remains poorly understood with very few well-identified validated targets for therapeutic purposes. In this study, we use nitric oxide (NO), which suppresses protein synthesis by inactivating eukaryotic initiation factor 2-alpha (eIF2-alpha), to examine the mechanism by which low and high oxidative stress inhibits protein synthesis. In breast cancer cells, low NO stress induced heme-regulated inhibitor (HRI) activation, which facilitated gradual decline in short half-life proteins. High NO stress induced HRI and protein kinase R (PKR) activation, leading to a sharp decline in protein synthesis as accessed by a decline in short and long half-life proteins and dramatic morphologic changes. In contrast, human mammary epithelial (HME) and Ras transfected untransformed HME (MCF-10A1 neo N) cells were less susceptible to NO-induced inhibition of protein synthesis and cytostasis. Our results suggest that NO-induced cytostasis in breast cancer cells was due to PKR activation and increased phosphorylation of eIF2-alpha, whereas the reduced susceptibility of normal mammary epithelial cells to NO could be due to the inaccessibility of PKR, which is bound to inhibitor p58.

Topics: Apoptosis; Blotting, Western; Breast; Breast Neoplasms; Cell Cycle; Cell Transformation, Neoplastic; Cells, Cultured; Culture Media, Serum-Free; Cyclic GMP; eIF-2 Kinase; Enzyme Activation; Eukaryotic Initiation Factor-2; Female; Free Radical Scavengers; Genes, ras; Heme; Humans; Hydrogen Peroxide; Immunoprecipitation; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Nitric Oxide; Oxidants; Oxidative Stress; Phosphorylation; Protein Biosynthesis; RNA, Small Interfering

Nitric oxide (NO) is produced by a group of synthase enzymes (NOS). By means of different pathways, NO exerts several functions in benign and malignant human bladder tissues. The current paper describes the NO/guanylate cyclase (sGC)/cyclic guanosine monophosphate (cGMP) and the NO/oxidative pathways in human bladder tissues.. Bladder carcinoma tissues were collected from 18 patients by transurethral resection procedures. Normal benign vesical tissue specimens from a further eight patients with benign diseases served as controls. Immunohistochemistry was conducted for localization of sGC, cGMP, and nitrotyrosine in benign and malignant vesical tissues, evaluating two-three tissue sections per patient.. Positive immunolabeling for sGC and cGMP was detected in vascular endothelial cells of normal and malignant vesical tissues. Those signals were most intense in bladder carcinoma tissues. Immunolabeling for sGC and cGMP was also detected in normal urothelial cells. In bladder carcinoma cells, a heterogeneous immunolabeling for sGC and cGMP was seen, with a wide spectrum of signal intensity. Positive immunostaining for sGC and cGMP was also observed in stromal round cells in benign and malignant bladder tissues. Immunolabeling for nitrotyrosine was mainly observed in endothelial cells, with a much stronger immunolabeling in bladder carcinoma tissues compared to normal benign controls. A weak immunolabeling for nitrotyrosine was also observed in bladder carcinoma cells. Normal urothelial cells did not show such nitrotyrosine expression.. The current report provides evidences that NO play several roles through different pathways in benign and malignant vesical tissues. The influences generated by NO molecules can be divided into cGMP-mediated effects (those resulting from the NO/sGC/cGMP pathway) and non-cGMP-mediated effects (those resulting from the NO/oxidative pathway). Increased angiogenesis is a cGMP-mediated effect, while nitrotyrosine production is a non cGMP-mediated oxidative effect. Such an NO/oxidative pathway is observed more often in bladder carcinoma.

Topics: Aged; Blotting, Western; Carcinoma; Cell Transformation, Neoplastic; Cyclic GMP; Free Radical Scavengers; Guanylate Cyclase; Humans; Immunohistochemistry; Neovascularization, Pathologic; Nitric Oxide; Nitric Oxide Synthase; Oxidation-Reduction; Tyrosine; Urinary Bladder Neoplasms

The presented model of controlled apoptosis has been based on the assumption that correct information exchange between an organism as a whole, and each of its cells is conditioned by mutual proportions of cAMP and cGMP concentrations (CcAMP, CcGMP), according to the formula CcAMP x CcGMP = 'a' (constant). The regulation of balance of these 'second messengers' in a cell and an extracellular space would depend on the mutual proportions of concentrations of Melatonin and monomers of Melanin. These indoloderived compounds could be the activators of the transcription factors i.e. RZR and NFkappa-B, regulating the expression of Prohormone Convertase (PC) gen and Nitric Oxide Synthase (NOS) gen, respectively. Additionally, maternal Melatonin and Nitric Oxide (NO), being able to pass through trophoblast or placenta freely, would play decisive role in the synchronization of embryogenesis and intrauterine development of the fetus. In case of an embryo or a fetus, the result of CcAMP and CcGMP multiplication, different from the proper constant 'a'-value, would mean occurrence of disorders in the structure and functioning of the cellular tensegrity system and, in consequence, disturbances in the intercellular information exchange. It would lead to deviation in cellular metabolism, oriented cell movement, uncontrolled apoptosis, and as a consequence, would lead to the development of fetal defects. In case of a child or an adult, a sudden occurrence and prolongation of such disturbances in CcAMP-CcGMP proportions would induce a process of apoptosis of normal cells and an initiation of a cancerogenesis. On the other hand, the recovery of equilibrium in the information exchange system would initiate apoptosis of neoplastic cells, and simultaneously, proliferation of connective tissue cells. According to the presented hypothesis, a decrease in CcAMP and destabilization of the CcAMP-CcGMP balance in an embryo or a fetus would result from relatively excessive amounts of maternal Melatonin (monomers) in fetal circulation, while a decrease of CcAMP and destabilization of the CcAMP-CcGMP balance in a child or an adult would be a consequence of relatively insufficient amounts of Melatonin (dimers) in an organism. It seems possible, that determination of both CcAMP and CcGMP would enable an early detection of high risk of developmental defects occurrence in an embryo or a fetus and neoplastic processes in a child or an adult. This method might also be considerably useful in moni

Topics: Apoptosis; Aspartic Acid Endopeptidases; Cell Transformation, Neoplastic; Cyclic AMP; Cyclic GMP; Dimerization; Embryonic and Fetal Development; Gene Expression Regulation, Enzymologic; Melatonin; Models, Theoretical; Proprotein Convertase 2; Proprotein Convertases; Receptors, Cell Surface; Receptors, Cytoplasmic and Nuclear; Receptors, Melatonin; Subtilisins

In order to search for new tumor differentiation inducer, the effects and mechanism of Icariin were studied.. Icariin is an monomer purified from Epimedium Koreanum Nakai. The differentiation of induction effects of Icariin were observed on the human promyelocytic leukemic cell (HL-60) by NBT reduction test, 125I-cAMP and 125I-cGMP double antibody radioimmune methods, scanning electronic microscopy technique.. After treating HL-60 cells with Icariin at concentration 0.1 g/L, reduction of NBT and cAMP/cGMP ratio were increased. There were many rugosities and ball-like processes on the cell surface.. Icariin had the effects of induction of differentiation on HL-60 cells, the mechanism might be related to elevating the cAMP/cGMP ratio.

Topics: Cell Transformation, Neoplastic; Cyclic AMP; Cyclic GMP; Drugs, Chinese Herbal; Flavonoids; HL-60 Cells; Humans

Di(adenosine-5')oligophosphate nucleotides of general structure ApnA (n = 2-6) inhibited phosphorylation of immunoglobulin G from tumor-bearing rabbits (TBR IgG) by pp60src protein kinase purified from Rous sarcoma virus-transformed rat tumor cells. Ap4A, a nucleotide associated with eukaryotic cell proliferation, was one of the most effective inhibitors in the series, causing 50% inhibition of TBR IgG phosphorylation at 15 microM. Ap4A inhibited pp60src-dependent phosphorylation of TBR IgG in solution and immunoprecipitates, as well as the phosphorylation of tubulin, microtubule-associated proteins, and vinculin. Under similar assay conditions, Ap4A did not inhibit phosphorylation of histone H2b by cAMP- or cGMP-dependent protein kinases. Ap4A appears to interact noncovalently with the enzyme, because removal of pp60src by immunoprecipitation from solutions containing Ap4A restored activity to uninhibited levels. A 100-fold increase in ATP (4-400 nM) caused a 13-fold increase in the 50% inhibitory concentration of Ap4A (2.5-33 microM), consistent with the interpretation that Ap4A competes for an ATP-binding site on the pp60src molecule. The simplest explanation of these results is that Ap4A binds to the phosphodonor site for ATP.

Topics: Adenine Nucleotides; Animals; Cell Line; Cell Transformation, Neoplastic; Cyclic AMP; Cyclic GMP; Dinucleoside Phosphates; Immunoglobulin G; Kinetics; Neoplasms, Experimental; Oncogene Protein pp60(v-src); Phosphorylation; Protein Kinases; Rabbits; Rats; Viral Proteins

Normal and Rous sarcoma virus (RSV)-transformed chick embryo fibroblasts growing on plastic dishes were incubated with ATP (gamma 32P) in situ to detect external cell surface protein kinase activity. Under the conditions employed, 32P was incorporated exclusively into proteins, specifically those at the external cell surface, as radioactivity was removed by trypsin treatment of labeled whole cells. In addition, exogenous histones were phosphorylated when added to the reaction mixture. Cyclic nucleotides had virtually no effect on 32P incorporation, suggesting that little or no cyclic nucleotide-dependent protein kinase activity was present at the external cell surface. Cell surface protein kinase activity was higher in transformed than in normal cells, and, using a temperature-sensitive RSV src mutant, this difference was shown to be transformation-specific. Several differences were observed in the cell surface proteins phosphorylated in normal and transformed cells and at least two of these were transformation-specific. These data suggest that changes in external cell surface protein phosphorylation are associated with RSV transformation and thus could play a role in the formation of the transformed cell phenotype.

Topics: Adenosine Triphosphate; Animals; Avian Sarcoma Viruses; Cell Line; Cell Transformation, Neoplastic; Cell Transformation, Viral; Chick Embryo; Cyclic AMP; Cyclic GMP; Fibroblasts; Membrane Proteins; Phosphorylation; Protein Kinases

Topics: Adenosine; Adenosine Monophosphate; Bucladesine; Butyrates; Cell Line; Cell Membrane; Cell Transformation, Neoplastic; Concanavalin A; Cyclic GMP; Receptors, Concanavalin A; Receptors, Drug; Theophylline; Trypsin

To investigate the role of guanosine 3':5'-monophosphate (cyclic GMP) in cultured cells we have measured guanylate cyclase and cyclic GMP phosphodiesterase activities and cyclic GMP levels in normal and transformed fibroblastic cells. Guanylate cyclase activity is found almost exclusively in the particulate fraction of normal rat kidney (NRK) and BALB 3T3 cells. Enzyme activity is stimulated 3- to 10-fold by treatment with the detergent Lubrol PX. However, enhancement of guanylate cyclase by fibroblast growth factor could not be demonstrated under a variety of assay conditions. In both NRK and BALB 3T3 cells guanylate cyclase activity is low during logarithmic growth and increases as the cells crowd together and growth slows. Guanylate cyclase activity is undetectable in homogenates of NRK cells transformed by the Kirsten sarcoma virus (KNRK cells) either in the presence or absence of Lubrol PX. Guanylate cyclase activity is also greatly decreased in NRK cells transformed by Moloney, Schmidt-Ruppin, or Harvey viruses. BALB 3T3 cells transformed by RNA viruses (Kirsten, Harvey, or Moloney), by a DNA virus (SV40), by methylcholanthrene, or spontaneously, all have diminished but readily detectable guanylate cyclase activity. Cyclic GMP phosphodiesterase activity is found predominately in the soluble fraction of NRK cells. This activity increases slightly as NRK cells enter the stationary growth phase. Cyclic GMP phosphodiesterase activity is undetectable in two clones of KNRK cells under a variety of assay conditions, and is decreased relative to the level present in NRK cells in a third KNRK clone. However, both Moloney- and Schmidt-Ruppin-transformed NRK cells have a phosphodiesterase activity similar to that found in NRK cells. Boiled supernatant from both NRK and KNRK cells is observed to appreciably enhance the activity of activator-deficient phosphodiesterase from bovine heart. This result indicates that the absence of cyclic GMP phosphodiesterase activity in KNRK cells is not due to a loss of the phosphodiesterase activator. The intracellular concentration of cyclic GMP is found to be very low in transformed NRK cells when compared to levels measured in confluent NRK cells. The low levels of cyclic GMP in transformed NRK cells reflect the greatly decreased guanylate cyclase activity observed in these cells. These results do not appear to support the suggestion that cyclic GMP promotes the growth of fibroblastic cells.

Topics: Cell Line; Cell Transformation, Neoplastic; Cyclic GMP; Enzyme Activation; Fibroblasts; Guanylate Cyclase; Kinetics; Manganese; Moloney murine leukemia virus; Oncogenic Viruses; Phosphoric Diester Hydrolases

Growth induction in resting fibroblast cultures by serum or growth factors induces a fast, transient cGMP peak which may constitute the intracellular signal for growth. A similar cGMP peak occurs when 3T3 cells arrested at the restriction point or in G0 by starvation for certain amino acids are induced for growth by readdition of the lacking nutrients. Both 3T3 and SV3T3 cells which are arrested randomly all around the cell cycle do not exhibit major changes in cyclic nucleotides after growth induction. Determination of intracellular cAMP and cGMP levels in normal and transformed fibroblasts under different growth conditions shows that the transition between growing and resting state (G0 arrest) is accompanied and probably induced by characteristic changes in cAMP to cGMP ratios. cGMP is decreased 2-5-fold in resting as compared to growing cultures, and increased 10-20-fold in activated cultures 20 min after serum induction. No major cGMP change was observed in growing, confluent, or serum-activated cultures of transformed cells. Measurement of guanylcyclase under unphysiological conditions (2 mM Mn++) in crude and purified membranes from 3T3 and SV3T3 cultures did not show increased enzyme activity in the transformed cells. Significant differences may only show up when synchronized cells pass through the restriction point in G1 phase. As a hypothesis it is proposed that transformed cells have an activated guanylcyclase system or a relaxed cGMP-pleiotypic response mechanism at the restriction point of their cell cycle.

Topics: Animals; Cell Division; Cell Line; Cell Transformation, Neoplastic; Culture Media; Cyclic AMP; Cyclic GMP; DNA Replication; Fibroblasts; Glutamates; Growth Substances; Histidine; Models, Biological; Polyomavirus; Simian virus 40

A survey of the available literature on the role of cyclic nucleotides (cyclic adenosine 3,5-monophosphate and cyclic guanosine 3,5-monophosphate) in the control over various aspects of cellular activity: regulation of growth and morphology of normal and tumorous cells, participation in differentiation of cells, blast-transformation, regulation of inflammatory and immunological processes governed by lymphocytes, is presented. A presumable mechanism of action of cyclic nucleotides is considered.

Topics: Animals; Antineoplastic Agents; Calcium; Cell Differentiation; Cell Transformation, Neoplastic; Cyclic AMP; Cyclic GMP; DNA; Enzyme Activation; Hormones; Humans; In Vitro Techniques; Liver Glycogen; Lymphocyte Activation; Mitosis; Neoplasms; Prostaglandins; Protein Kinases

Mouse fibroblasts transformed by simian virus 40 (SV3T3 cells) are characterized by cyclic AMP and cyclic GMP levels, respectively, about half and twice those found in growing untransformed 3T3 cells. Density-dependent inhibition of growth is correlated with reduced cyclic GMP concentrations in 3T3 and four different density-restricted revertant lines derived from SV3T3. The levels of cyclic AMP are not increased at confluence. Upon serum restriction, serum-dependent cell lines show a greater increase in intracellular cAMP than serum-insensitive lines. Cyclic GMP levels are greatly reduced, even in serum-insensitive density revertants, but not in SV3T3. Serum readdition to all serum-dependent lines is followed by a rapid decrease in cyclic AMP and increase in cyclic GMP concentrations. The magnitude of these responses is decreased in SV3T3 and density revertants.

Topics: Animals; Blood; Cell Division; Cell Line; Cell Transformation, Neoplastic; Contact Inhibition; Culture Media; Cyclic AMP; Cyclic GMP; Fibroblasts; Kinetics; Mice; Simian virus 40

Topics: 3',5'-Cyclic-AMP Phosphodiesterases; Animals; Bucladesine; Cell Transformation, Neoplastic; Cells, Cultured; Chromatography, Ion Exchange; Cyclic GMP; Dactinomycin; Enzyme Activation; Fibroblasts; Mice; Phosphoric Diester Hydrolases; Simian virus 40

Topics: 3',5'-Cyclic-AMP Phosphodiesterases; Adenylyl Cyclases; Bucladesine; Catecholamines; Cell Aggregation; Cell Division; Cell Line; Cell Transformation, Neoplastic; Cells, Cultured; Clone Cells; Contact Inhibition; Cyclic AMP; Cyclic GMP; Enzyme Activation; Fibroblasts; Hybrid Cells; Models, Biological; Mutation; Protein Kinases

Topics: Binding Sites; Cell Adhesion; Cell Aggregation; Cell Division; Cell Membrane; Cell Transformation, Neoplastic; Cyclic AMP; Cyclic GMP; Enzyme Inhibitors; Glucose; Glycosaminoglycans; Lectins; Models, Biological; Peptide Hydrolases; Phenotype; Plasminogen; Protease Inhibitors; Proteins; Thrombin; Tosyllysine Chloromethyl Ketone; Tosylphenylalanyl Chloromethyl Ketone; Trypsin Inhibitors; Viruses

Topics: Animals; Cell Transformation, Neoplastic; Cells, Cultured; Cyclic AMP; Cyclic GMP; Mice; Simian virus 40

Topics: Animals; Cell Division; Cell Line; Cell Transformation, Neoplastic; Culture Media; Cyclic AMP; Cyclic GMP; Fibroblasts; Mice

Topics: Animals; Avian Sarcoma Viruses; Cell Division; Cell Transformation, Neoplastic; Chick Embryo; Contact Inhibition; Culture Techniques; Cyclic AMP; Cyclic GMP; DNA; Fibroblasts; Insulin; Neuraminidase; Nucleotides, Cyclic; Phosphates; Phosphoproteins; Phosphoric Diester Hydrolases; Phosphorus Radioisotopes; Protein Kinases; Stimulation, Chemical; Thymidine; Tritium

Topics: Animals; Cell Adhesion; Cell Line; Cell Membrane; Cell Transformation, Neoplastic; Cells, Cultured; Chelating Agents; Colchicine; Cricetinae; Cyclic AMP; Cyclic GMP; Cytochalasin B; Dexamethasone; Ethylene Glycols; Kidney; Microscopy, Phase-Contrast; Microtubules; Polyomavirus; Theophylline

Topics: Animals; Cell Division; Cell Line; Cell Transformation, Neoplastic; Cyclic AMP; Cyclic GMP; DNA; Fibroblasts; Kidney; Leucine; Methionine; Mice; Mice, Inbred BALB C; Mice, Inbred Strains; Prostaglandins; Simian virus 40; Tritium

Topics: Adenosine Monophosphate; Animals; Blood; Butyrates; Cell Division; Cell Line; Cell Transformation, Neoplastic; Cyclic AMP; Cyclic GMP; Cytosine Nucleotides; Depression, Chemical; DNA; Fibroblasts; Insulin Antagonists; Lectins; Mice; Peptide Hydrolases; Polyomavirus; Protease Inhibitors; Thymidine; Thymine Nucleotides; Tritium